Method and apparatus for pre-caching in a telecommunication system

ABSTRACT

The present invention relates to file pre-caching and file retrieving in an autonomous network access module comprising a local storage, and providing network connectivity to a mobile device in a telecommunication system. The network access module comprises a local storage and provides network connectivity to a mobile device ( 100 ) within which it is comprised. A received file request to a global radio network ( 10 ) from the mobile device ( 100 ) is intercepted, where after the file is searched for among available pre-cached files, which may reside within the local storage controlled by the network access module itself, or within a local storage of a peer network access module in a local radio network  70 . If the file is found within available pre-cached files, it is transparently transferred over a bus interface to the requesting mobile device. During transfer, the amount of data is measured, and the measurements are subsequently used during an accounting stage where charging related information is reported to a charging module  80  in the global radio network  10 . Files may be pre-cached in a distributed storage comprised by a group of network access modules conjoined by a local radio network  70 . Files allotted for pre-caching by a network operator are received and stored in network access modules but are not billed unless the files are actually consumed.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a 35 U.S.C. §371 national stage application of PCTInternational Application No. PCT/SE2009/051268, filed on 6 Nov. 2009,the disclosure and content of which is incorporated by reference hereinin its entirety. The above-referenced PCT International Application waspublished in the English language as International Publication No. WO2011/056108 A1 on 12 May 2011.

TECHNICAL FIELD

The present invention relates to file pre-caching and file retrieving inan autonomous network access module comprising a local storage, andproviding network connectivity to a mobile device in a global radionetwork.

BACKGROUND

With increasing popularity of content streaming services such asYouTube© and Spotify©, the number of users in the mobile space isincreasing, and the average traffic load with them. The innovators andearly adopters of yesterday are now expecting their mobile devices tohandle download faster than before with maintained quality and security.In the wake comes the early-majority comprising experienced desktopusers projecting desktop user experience expectations onto the mobiledevice.

Mobile networks typically feature a wide traffic dispersion range. Theload during a few solitary peak hours per day may be 20 times as high asthe average traffic load, whereas the load during, say eight,minimum-traffic hours is virtually zero. The traffic load also varies ona weekly and seasonal basis. An un-balanced network must in effect bedesigned to handle peak level traffic 24-7, all year round, in order toavoid disgruntled customers during the relatively few peak hours. Duringthe off-peak hours, that un-balanced network is consequently anunder-deployed liability, rendering lower Return On Assets, tostakeholders' dismay.

Various load-balancing methods have been presented to address the aboveproblems, but in doing so, they cause new ones. According to one method,the delivery of non-critical traffic, e.g. file downloads, is reduced ordelayed during peak hours. This is a very crude way of load-balancing,which certainly enables increased system deployment, but at the expenseof service quality.

Other methods attempt to cache content locally so that the network doesnot need to be invoked when the user requests the content. The mostcommon ones are client “agents”, e.g. Google Web Accelerator©, thatsilently download files a user is likely to access and store it locallyuntil the user requests it. The method reduces peak load at the expenseof an acceptable increase in average load. However, the network operatorcannot distinguish pre-downloading traffic from other traffic and willtherefore bill the end-user for downloading of content that was neitherrequested nor consumed. This is a major disincentive to employingpre-downloading software.

Yet other methods send encrypted data to the client proactively, storingit as an encrypted file on the system, and then either sending a“decrypt” signal from the network or allowing the user to request orpurchase the key to decrypt the data with. The sent data is consideredproperty of the network operator until decrypted. The transfer is notbilled, but the act of unlocking the data is. However, these method arenon-transparent, as the end result is encrypted data, which may perhapseven require user interaction to purchase an unlock key. They are alsosusceptible to software tampering.

SUMMARY

It is the object to obviate at least some of the above disadvantages andprovide improved inter-related methods, apparatuses and computer mediaproducts avoiding the above mentioned drawbacks.

A first aspect of the invention relates to two inter-related methods forfile pre-caching and file retrieval in an autonomous network accessmodule comprising a local storage and providing network connectivity toa mobile device in a global radio network. The first inter-relatedmethod comprises the steps: receiving a file request to the global radionetwork from the mobile device; intercepting the file request; searchingfor the requested file among available pre-cached files; if the file isfound enabling the mobile device to access the file; measuring theamount of data transferred to the mobile device via a bus from thenetwork access module; and accounting for the amount of datatransferred, to a charging module in the global radio network.

The method may further comprise the step: receiving and storing in thelocal storage a file comprising meta data, allotted for pre-caching byan operator of the global radio network. The searching step may furthercomprise searching for the requested file in the local storage.

The searching step may alternatively or also further comprise searchingfor the file in a local storage of a peer network access module in alocal radio network.

When searching among available files in peer network access modules, thesearching step may further comprise broadcasting a file request in thelocal radio network; and awaiting an availability confirmationcomprising meta data from the peer network access module in the localradio network.

The step of enabling, upon receiving an availability confirmation,further comprises the steps: sending a second file request to the peernetwork access module in the local radio network; and receiving therequested file from the peer network access module over the local radionetwork.

The method may comprise receiving a credit allowance from a chargingmodule in the global radio network.

The method may further comprise the step estimating file size againstremaining credit allowance; and the enabling step being contingent uponthe estimation that the data transfer can be made within the remainingcredit allowance.

The first aspect's second inter-related method relates to filepre-caching and file retrieving in an autonomous network access modulecomprising a local storage and providing network connectivity to amobile device in a global radio network comprising the steps: receivingand storing in the local storage a file comprising meta data, allottedfor pre-caching by an operator of the global radio network; receiving abroadcast file request from a peer network access module in a localradio network; searching for the requested file among available files inthe local storage; and if found enabling the peer network access moduleto access the file.

The enabling step may comprise the step: sending an availabilityconfirmation to the peer network access module, comprising meta data;and may further comprise the steps awaiting a second request for thesame file from the peer network access module; and upon reception of thesecond request, sending the file to the peer network access module overthe local radio network.

A second aspect of the invention relates to two inter-related networkaccess modules, each comprised within mobile devices, and comprisinglocal storages, radio transceivers and processing units, each connectedto the mobile devices via bus interfaces.

The first network access module is adapted and configured to receive afile request to the global radio network from the mobile device;intercept the file request; search for the requested file amongavailable pre-cached files; if found enable the mobile device to accessthe file; measure the amount of data transferred to the mobile devicevia a bus from the network access module; and account for the amount ofdata transferred, to a charging module in the global radio network.

The network access module may be adapted to receive and store in thelocal storage a file comprising meta data, allotted for pre-caching byan operator of the global radio network. It may further be adapted tosearch for the requested file in the local storage; and if found enablethe mobile device to access the file.

The network access module may further be adapted to broadcast a filerequest in a local radio network; and await an availability confirmationcomprising file size from the peer network access module in the localradio network.

In the enabling step, upon receiving an availability confirmation, thenetwork access module is further adapted to send a second file requestto the peer network access module in the local radio network; and toreceive the requested file from the peer network access module over thelocal radio network.

The network access module may be adapted to receive a credit allowancefrom a charging module in the global radio network.

The network access module may be adapted to estimate file size againstremaining credit allowance; and enable the mobile device to access thefile contingent upon estimating that data transfer can be made withinthe remaining credit allowance.

The second network access module according to the second aspect of theinvention is adapted and configured to receive and store in the localstorage a file comprising file size, allotted for pre-caching by anoperator of the global radio network; receive a broadcast file requestfrom a peer network access module in a local radio network; search forthe requested file among available files in the local storage; and iffound enable the peer network access module to access the file.

The network access module may be adapted to send an availabilityconfirmation to the peer network access module, comprising file metadata.

The network access module may further be adapted to await a secondrequest for the same file from the peer network access module; and uponreception of the second request send the file including meta data to thepeer network access module over the local radio network.

A third aspect of the invention relates to a computer program comprisingcode means for performing the steps of any method embodiment of thefirst aspect when the program is run on a computer.

A fourth aspect of the invention relates to a computer program productcomprising program code means stored on a computer readable medium forperforming the steps of any method embodiment of the first aspect, whensaid product is run on a computer.

The intercepting characteristic of aspects of the invention enables themto be transparent to the mobile device 100 and thus transparent to theuser. Since the searching characteristics involve searching amongavailable files it enables a distributed pre-cache storage. Because thenetwork access module is autonomous against its mobile device, theenabling characteristic is central, as this is the only way the mobiledevice will get access to the file. The measuring and accountingcharacteristics enables charging of the actual file consumptionpost-caching and consequently to bill the user for actually consumedfiles instead of yet un-consumed files received for pre-caching. It alsoenables accumulative reporting, thus reducing the amount of reportingmessages to the charging module. All the aspects reduce trafficdispersion ranges in a network, increase Quality of Service and enablevery short delivery times and eliminate billing of un-requested data ina transparent manner.

For the purpose of completeness, the word file should be interpreted ina wide sense to include all sorts of data structures, and network-basedresources. Further, with “charging” is meant a collection of proceduresgenerating charging data. With “billing” is meant a procedure thatpost-processes charging data and produces a bill for the end-user.Un-billed traffic is not necessarily un-charged, but the charging datahas not affected the end-users bill.

BRIEF DESCRIPTION OF THE DRAWINGS

In order to explain the invention in more detail an embodiment of thepresent invention will be described in detail below, reference beingmade to the accompanying drawings, in which

FIG. 1 is an overview of the system in which embodiments of theinvention are implemented.

FIG. 2 is a schematic illustration of two mobile devices 100 and 200.

FIG. 3 is a flow-chart illustrating a method according to oneembodiment.

FIG. 4 is a sequence diagram illustrating an inter-related methodaccording to one embodiment.

FIG. 5 is a flow-chart illustrating a method according to one embodimentof the invention.

DETAILED DESCRIPTION

The system in which the present invention is implemented will now bedescribed in relation to FIG. 1. Within a global radio network 10,operated by a network operator, a pre-cache and prediction service 20 isimplemented, which manages and sends files allotted for pre-cachingbased on network and device specific conditions set by the networkoperator. The actual files are dispatched from a remote web server 30,and may be sent to network access modules comprised within mobiledevices 100, 200 connected to the global radio network 10. Even thoughmobile device 100 may not have received any files for pre-caching andeven though the mobile device 100′ is not connected to the global radionetwork, they may still have access to pre-cached files within themobile device 200. Besides the global radio network 10, another, local,radio network 70 is depicted in FIG. 1. The global radio network 10 alsocomprises a charging module 80. When a mobile device 100 with acompatible network access module connects to the global network 10, thepre-caching and prediction service 20 is informed of the network accessmodule's existence and the amount of local storage available, as well asthe data stored in the network access module's local storage. When theconditions for pre-caching are fulfilled, files allotted for pre-cachingmay be sent to the connecting mobile device. This traffic isdifferentiable from regular end-user generated traffic in the globalnetwork 10 and is not billed.

Pre-caching conditions can be one or many of a non-conclusive list suchas: a network access module being connected to the global network 10,sufficiently low deployment level in certain network entities, such ase.g. a network server or router or groups of servers or routers,sufficiently low general traffic load in the global network 10, a mobiledevice having enough battery power to sustain pre-caching, a networkaccess module having enough available local storage, a local radionetwork 70 being available to a network access module. That local radionetwork 70 may be a WPAN or ad-hoc network such as Bluetooth© or WiFi. Akey concept in WPAN technology is known as “plugging in”. In the idealscenario, when any two WPAN-equipped devices come into personaloperating space they can communicate peer-to-peer as if connected by acable. Therefore, pre-cached files stored in the local storage of onenetwork access module is available to that network access module, ofcourse, but also available to any other network access module that maybe connected over the local radio network 70.

A network access module comprised within a mobile device 100 will now bedescribed in relation to FIG. 2 a. FIG. 2 a displays a mobile device100, such as for instance a mobile phone. The mobile device 100comprises a main processing unit 110 and a network access module 120,which provides network connectivity to the mobile device 100. Thenetwork access module 120 comprises a first transceiver 130 adapted forthe global radio network 10, a second transceiver 140 adapted for thelocal radio network 70, a local processing unit 150 and a local storage160. The local storage 160 has a larger capacity compared toconventional network access modules, and is adapted to provide storagefor un-billed pre-caching within the network access module 120. Further,a data bus 180 constitutes the interface between the network accessmodule 120 and the mobile device 100. Because of the bus 180, anyresource request from the mobile device 100 must be processed by thenetwork access module's 120 processing unit 150, even for resourcesavailable within the local storage 160. The bus interface 180 henceentails a natural isolation of the network access module 120 from themobile device 100, and the network access module 120 can thereforeautonomously manage the mobile devices 100 access to data stored in thelocal storage 160. This autonomy makes it possible for the networkoperator to have a considerable level of trust for the network accessmodule 120, and to consider the local storage 120 to be a secure placefor pre-caching, even though the mobile device 100 may not be trustedfor pre-caching. FIG. 2 b displays a mobile device 200 comprising a mainprocessing unit 250 and a network access module 220 which in turncomprises a first and second transceiver 230, 240, a local processingunit 250, a local storage 260 and a data bus 280. These components arearranged in analogy with the components of the mobile device 100 andconfigured and adapted in a related way.

One embodiment of the present invention will now be described inrelation to FIG. 3. When the mobile device 100 is requesting a file, thenetwork access module 120 is receiving a file request to the globalradio network 10 from the mobile device 100 via the bus 180. The networkaccess module 120 is then intercepting the file request; it is notexpediting it the way the mobile device 100 intended. It is possible toperform the interception in a network-based proxy, rewriting the file'saddress to unequivocally point to data on the network module. However,this requires either a software component specific to the mobile devicesoperating system or a network component and network access.

Instead of immediately forwarding the request to the global network 10,the network access module 120 is searching for the requested file amongavailable pre-cached files. Each file is associated with a globallyunique identifier, e.g. URI's for web content, which the network accessmodule 120 is using in its search.

If the file is found among available pre-cached files, the networkaccess module 120 is enabling the mobile device 100 to access the filein a step that comprises opening the bus 180 interface for the mainprocessing unit of the mobile device. While the file is beingtransferred, the network access module 120 is measuring the amount ofdata transferred to the mobile device 100 via the bus 180 from thenetwork access module 120. In a next step, the network access module 120is accounting for the amount of data transferred, to a charging module80 in the global radio network 10. This may be done through the networkaccess module 120 computing certain intermediate figures based on themeasurements and reporting the measured amount of transferred data tothe charging module 80.

If the file was not found, the network access module 120 may forward theoriginal file request to the global network 10. If the mobile device 100registered on the global network 10 during peak hours, the pre-cachingand prediction service 20 will not yet have had opportunity to orderpre-caching of allotted files. The local storage 160 may then becompletely empty.

In one embodiment, a pre-caching step is comprised, in which the networkaccess module 120 is receiving and storing in the local storage 160 afile comprising meta data, allotted for pre-caching by an operator ofthe global radio network 10. The meta data comprises file size and mayalso comprise other information. This step enables the network accessmodule 120 to store available pre-cached files within its own housing.During the searching step, the network access module 120 may then besearching for the requested file in the local storage 160 it controlsitself.

The local storage 160 may still be empty because the network operatormay e.g. have found malware in copies of the file in the global network10 and decided to destroy all available copies. Lastly, the predictionservice 20 may just have failed to predict this particular request, andmay have stored allotted several other un-billed pre-cached files forstoring in the local storage 160.

In one embodiment of the invention, the searching is made amongavailable pre-cached files stored within a group of peers in a localradio network 70. The network access module 120 may decide to do thisupon first searching its own local storage 160, but it may also decideto do this as a first measure. The reason for this may be that thenetwork access module 120 knows it has not received any files, or thatits local storage 160 is empty for other reasons. Further it may nothave the full capacity allowing it to pre-cache in its own local storage160.

In this embodiment the searching step further comprises broadcasting afile request in the local radio network 70. The broadcast comprises theglobally unique identifier of the requested file and reaches all peerswith available pre-cached files. The network access module 120 is thenawaiting an availability confirmation comprising meta data from the peernetwork access module 220 in the local radio network 70, whose responsefirst reached the broadcasting network access module 120.

Upon receiving an availability confirmation, the network access module120 is sending a second file request to the peer network access module220 in the local radio network 70 and receiving the requested file fromthe peer network access module 220 over the local radio network 70.

One embodiment of the present invention will now be described inrelation to FIG. 5. In this embodiment the network access module 120 isreceiving a credit allowance from a charging module 80 in the globalradio network 10, regularly or prompted by certain events or uponrequest from the network access module 120 itself. Before making thefile available to the mobile device 100, the network access module 120is estimating the file size, which has been stored together with thefile in the local storage 160, or received as meta data in anavailability confirmation, against remaining credit allowance. Thenetwork access module 120 is then enabling the mobile device 100 toaccess the file only if there is enough credit to do so, i.e. theenabling is further contingent upon the estimation that data transfercan be made within the remaining credit allowance. During the accountingstep, the network access module 120 is arithmetically computing a newremaining credit allowance. This may comprise deducting creditscorresponding to measured transferred data from the remaining creditallowance.

The step of reporting the measured amount of transferred data to thecharging module 80 may be done directly or it may be done uponaccumulating the results of several measurements, i.e. after enablingthe mobile device 100 access to several files. The reporting may be donein terms of remaining credit allowance, amount of consumed credit unitsor measured bytes or a combination. The figures may be reported as onecumulative sum or a set of transaction posts. The network operator maye.g. have an interest in knowing what files where consumed in theirentirety, what users tend to interrupt downloading etc.

The embodiment that comprises reception of a credit allowance enablesleeway in charging for files consumed by the network access module 120.Not having to report charging information immediately is advantageousespecially when e.g. loading a multitude of small files, such as imagefiles e.g., from the local storage 160. It reduces processing load andconserves battery on the module side, but also reduces global network 10load as well as processing load in the charging module 80. For thepurpose of illustration, one credit unit may correspond to one byte ofdata transferred over the bus 180. When the network access module 120 ispowered on and connected to the network, it announces its presence tothe charging module 80 in the global radio network 10, using anidentification message that includes sufficient data about the networkaccess module 120, such as version, vendor, security features or otherthings, thus allowing the charging module 80 to determine thetrustworthiness of the network access module 120. Based on thetrustworthiness, the charging module 80 may be granting the networkaccess module 120 a given amount of credit units, ranging from no creditunits if the network access module 120 cannot be trusted to properlyreport the data transferred, to practically unlimited credit for a flatrate data plan. The exact size of the credit allowance is a tradeoffbetween charging practices, network optimization and risk adversity ofthe network operator. The credit allowance may have an expiration timeafter which the network access module 120 must either request a newcredit allowance from the charging module 80 or refrain from using thelocal storage 160. For the running illustration, the charging module 80may decide to grant the network access module 120 a credit allowance of1000 credit units, to expire in one hour. When the mobile device 100requests access to a network-based resource, e.g. a file, and that filecan be found among available pre-cached files, the network access module120 can enable access to it contingent upon the estimation that datatransfer can be made within remaining credit units. In the currentillustration, the mobile device 100 requests a file comprising 500 bytesof data. Since 1000 credit units where given, and each transferred byteconsumes 1 credit unit, the file can be served from the local storage160. 500 credit units are consumed from the network access module's 120credit allowance. The consumed credit may be reported to the chargingmodule 80 in various ways. It may be reported when the credit allowanceis fully consumed, when the remaining credit units have expired, whenmore credit units are needed to fully serve a file, or when some otherform of network activity occurs, such as e.g. a phone call, or someother form of service charging that might affect available money on anetwork operator account. In the case of a pre-paid account, calling mayreduce the amount of available money, and, consequently, bandwidth. Thenetwork access module 120 must then report/request a new creditallowance in order to not overdraw the pre-paid account.

It is also possible to attempt to predictively request a creditallowance. In the running illustration, since only 500 credit units wereconsumed, 500 remain; there is no need to request a new creditallowance. The network access module 120 may then wait for the nextrequest, or await expiration of the remaining credit allowance. At thatpoint the network access module 120 reports the credit usage, whilesimultaneously requesting a new credit allowance. Based on past usagehistory and trustworthiness, the charging module 80 may vary creditallowance size and expiration period.

At the charging module 80 discretion, the remaining credit allowance maybe nullified by the charging module 80 sending a credit nullificationmessage to the network module.

An inter-related method according to an embodiment of the presentinvention will now be described in relation to FIG. 4.

It is a method for file pre-caching and file retrieval in an autonomousnetwork access module. The network access module comprises a localstorage, and is operating in the system depicted in FIG. 1.

In a pre-caching step, the network access module 220 is receiving andstoring in the local storage 260 a file comprising meta data, allottedfor pre-caching by an operator of the global radio network 10. It isfurther receiving a broadcast file request from a peer network accessmodule 120 in a local radio network 70. The broadcast file requestcomprises a globally unique identifier that the network access module220 is using during searching for the requested file among availablefiles in the local storage 260.

If the file is found, the network access module 220 is enabling the peernetwork access module 120 to access the file.

The enabling may be done such that the network access module 220 issending an availability confirmation to the peer network access module260, comprising meta data.

Further the enabling step comprises the step of awaiting a secondrequest for the same file from the peer network access module 120; andupon reception of the second request, sending the file to the peernetwork access module 120 over the local radio network 70.

To further facilitate the peer-to-peer mode of operation, the networkaccess module 220 can use any remaining available storage in the localstorage 260 for any data traffic downloaded, i.e. also for filesreceived through billed downloading. These additional files, which werenot predicted by the prediction service 20, can then also be served toother network access modules 100 and 100′ within personal operationspace. These peer-to-peer transfers are also encrypted, thus reducing orpreventing data leakage.

Since the network access module 220 is trusted by the network operator,any pre-cached file in the local storage 260, which turns out tocomprise malware, can be efficiently removed and destroyed.

The number of pre-cached files available to each mobile device ismultiplied if it can be retrieved from peers in a local network 70. Thisis an advantage to the end-user of the mobile device in question, as theaverage delivery time is correspondingly reduced when even less filesmust be requested from the global network 10. The method also enablesaccess to global network 10 content, even though the mobile device maynot actually be connected to the global network 10, or even in fact tothe local network 70. The method also additionally reduces the trafficcaused by mobile device requests. Further, this mitigates the moderateaverage traffic load increase caused by pre-caching.

As an example, in a situation where the pre-caching and predictionservice 20 manages a group of files that are so frequently requestedthat they must be pre-cached and made available to all mobile devices inthe global network 10, the related pre-caching traffic generated is filegroup size times number of mobile devices in the global network 10.

However, humans are social creatures of habit. Therefore, in all globalradio networks, there will be collectives of mobile device's, themembers of which by some satisfactory level of probability areinterconnected via local radio networks. The pre-caching and predictionservice 20 can analyze these collectives and decide to pre-cache the tenfiles only once collective as a whole and for most cases for eachindividual mobile device. The local radio link does not significantlyincrease delivery time of pre-cached content, the average delivery timeis even further reduced, and peak traffic load further reduced when evenless files must be requested from the global network 10. Further, thissignificantly reduces the average traffic load caused by pre-caching.

The aspects of the invention give many advantages. Firstly, if availableamong pre-cached files, the file can be delivered instantly. Secondly,the global network 10 load will not be affected by this particular filerequest of the mobile device 100. This means that even thoughpre-caching according to embodiments of this invention may cause amoderate average traffic load increase, it significantly lowers the peaktraffic load induced by mobile device 100 requests, which in turnenables a higher network deployment.

Further, aspects of the invention allow the pre-caching of data, thussmoothing out the network traffic curve, while enabling billing theend-user for consumed data only. It does so in a way that allows thenetwork operator to know that the data is properly accounted for, whilenot requiring additional network access for reporting charginginformation, and being completely transparent to all of the device'sapplications.

In addition, it enables a distributed pre-cache, distributed overnetwork access modules within each others personal operating space andconstituting a larger pre-cache storage, which has a better chance ofcontaining requested information. This enables increased networkoperator data traffic revenue while reducing network load, since thesame pre-cached file is available to and can be subsequently sent toseveral peer network access modules over a local radio network 70.

Because the pre-caching network access module is capable of operatingindependently of the main mobile device's processing unit, it ispossible for the network access module to remain active while the mobiledevice's processing unit is shut off, in order to reduce powerconsumption while retaining the ability to provide the device with newdata from the network, and retaining the ability to keep the pre-cachedfiles available to other network access module's

Because of the pre-cached data being available, the end-user experienceis improved, since there is no global radio network round-trip time.

Solutions according to aspects of this invention are superior to anencryption/unlock solution as the latter requires both global radionetwork round-trip time and decryption overhead time after the file isrequested, thus partially or fully negating any performance benefitgained by pre-caching.

The invention claimed is:
 1. A method for file pre-caching and fileretrieving in an autonomous network access module comprising a localstorage, and providing network connectivity to a mobile device in aglobal radio network, the method comprising the steps of: receiving afile request to the global radio network from the mobile device;intercepting the file request; searching for the requested file amongavailable pre-cached files and responding to finding the file by thefurther steps of,  enabling the mobile device to access the file, measuring the amount of data transferred to the mobile device via a busfrom the network access module, and  accounting for the amount of datatransferred, to a charging module in the global radio network; receivinga credit allowance from a charging module in the global radio network;and estimating the file size against remaining credit allowance, whereinthe enabling step is further contingent upon the estimation that datatransfer can be made within the remaining credit allowance.
 2. Themethod according to claim 1, further comprising the step of receivingand storing in the local storage a file comprising meta data, allottedfor pre-caching by an operator of the global radio network.
 3. Themethod according to claim 1, wherein the searching step furthercomprises: searching for the requested file in the local storage.
 4. Themethod according to claim 1, wherein the searching step furthercomprises: searching for the file in a local storage of a peer networkaccess module in a local radio network.
 5. The method according to claim4, wherein the searching step further comprises: broadcasting a filerequest in the local radio network; and awaiting an availabilityconfirmation comprising meta data from the peer network access module inthe local radio network.
 6. The method according to claim 5, wherein thestep of enabling, upon receiving an availability confirmation, furthercomprises the steps of: sending a second file request to the peernetwork access module in the local radio network; and receiving therequested file from the peer network access module over the local radionetwork.
 7. A method for file pre-caching and file retrieving in anautonomous network access module comprising a local storage andproviding network connectivity to a mobile device in a global radionetwork, the method comprising the steps of: receiving and storing inthe local storage a file comprising meta data, allotted for pre-cachingby an operator of the global radio network; receiving a broadcast filerequest from a peer network access module in a local radio network; andsearching for the requested file among available files in the localstorage and responding to finding the file by enabling the peer networkaccess module to access the file, wherein the enabling step furthercomprises the step of sending an availability confirmation to the peernetwork access module, comprising meta data.
 8. The method according toclaim 7, wherein the enabling step further comprises the steps of:awaiting a second request for the same file from the peer network accessmodule; and responding to reception of the second request by sending thefile to the peer network access module over the local radio network. 9.A network access module comprised within a mobile device, the networkaccess module comprising a local storage, a radio transceiver and aprocessing unit, connected to the mobile device via a bus interface,adapted and configured to: receive a file request to the global radionetwork from the mobile device; intercept the file request; search forthe requested file among available pre-cached files; and respond tofinding the file by:  enabling the mobile device to access the file, measuring the amount of data transferred to the mobile device via thebus from the network access module, and  accounting for the amount ofdata transferred, to a charging module in the global radio network;receive a credit allowance from a charging module in the global radionetwork; estimate the file size against remaining credit allowance; andenable the mobile device to access the file contingent upon estimatingthat data transfer can be made within the remaining credit allowance.10. The network access module of claim 9 further adapted and configuredto: receive and store in the local storage a file comprising meta data,allotted for pre-caching by an operator of the global radio network. 11.The network access module of claim 9 further adapted and configured to:search for the requested file in the local storage; and respond tofinding the file by enabling the mobile device to access the file. 12.The network access module of claim 11 further adapted and configured to:broadcast a file request in a local radio network; and await anavailability confirmation comprising file size from the peer networkaccess module in the local radio network.
 13. The network access moduleof claim 12, wherein the enabling step, upon receiving an availabilityconfirmation, further is adapted and configured to: send a second filerequest to the peer network access module in the local radio network;and receive the requested file from the peer network access module overthe local radio network.
 14. A network access module comprised within amobile device, and comprising a local storage, a radio transceiver and aprocessing unit, connected to the mobile device via a bus interface,adapted and configured to: receive and store in the local storage a filecomprising file size, allotted for pre-caching by an operator of theglobal radio network; receive a broadcast file request from a peernetwork access module in a local radio network; search for the requestedfile among available files in the local storage; respond to finding thefile by enabling the peer network access module to access the file; andsend an availability confirmation to the peer network access module,comprising file meta data.
 15. The network access module of claim 14further adapted and configured to: await a second request for the samefile from the peer network access module; and respond to receipt of thesecond request by sending the file including meta data to the peernetwork access module over the local radio network.